U.S. military and CIA personnel are training antiterrorist units for foreign governments as part of the Reagan administration's stepped-up policy of combating terrorism around the world, according to U.S. officials.

The unpublicized program is designed to increase the ability of allied governments to thwart hostage-taking, airplane hijackings and other terrorist acts through special antiterrorist squads patterned after the U.S. military's elite Strike Force Delta that carried out a failed 1980 mission to rescue American hostages in Iran, officials said.

The training has been conducted in about a dozen countries, including Lebanon and Honduras, the officials said.

"It's part of a worldwide program," said one U.S. government official. "It's been very successful."

Information on the program was furnished to The Washington Post on a not-for-attribution basis by civilian government officials and military sources after reporters learned of the Honduran training operation. Their descriptions provide a rare glimpse of sensitive operations carried out by the CIA and the U.S. military in the little-publicized war on terrorism that the Reagan administration has made a high priority of its foreign policy.

The counterterrorist assistance also has included use of U.S. personnel to advise a foreign government while a terrorist act is in progress. For example, during a recent hostage-taking in Sudan, CIA and U.S. military personnel advised the Sudanese, and intelligence picked up by U.S. spy satellites was turned over to them. The information helped Sudanese authorities pinpoint the location of the abductors, who were linked to a secessionist southern rebel group.

U.S. personnel also advised Thailand during an airplane hijacking in that country.

It is unclear when the United States began providing counterterrorism training to foreign governments. Some sources said the United States has been providing "security training" to foreign governments for about 10 years. But the program clearly has picked up under the Reagan administration.

Officials said the effort is kept secret because individual countries might not want it known that the United States is providing such sensitive aid or might believe that publicizing it could tip off a potential terrorist group. In Honduras, for example, members of a 40-man U.S.-trained antiterrorist squad, the Urban Operations Command, have at times been portrayed as members of a regular internal security force called the Cobras, military sources said.

"It tells people something if they know we have the capability," said one official. "And it might embarrass the host country that we are training them."

The counterterrorist training in Honduras was carried out by U.S. Army Special Forces personnel, or Green Berets, in collaboration with the CIA.

Code-named "Operation Quail Shooter" by the U.S. military, the training was conducted in strict secrecy at the Honduran Army's Special Forces Command at La Venta, a small military installation about 22 miles north of Tegucigalpa, the Honduran capital.

According to a source familiar with the program, the Green Berets posed as civilians, wore jeans and other casual clothes and were ordered to stay away from other U.S. military personnel stationed in Honduras. They traveled to Honduras aboard regular commercial aircraft and received identification papers saying they were civilian engineers.

Rep. Michael D. Barnes (D-Md.), who has been critical of the administration's Central American policy as chairman of the House subcommittee on Western Hemisphere affairs, said Congress should examine the training program. Barnes said through a spokesman that disclosure that the military had been involved with the CIA in a secret training program in Honduras at the same time the CIA was directing the covert war against Nicaragua raises new questions about the military's true role there.

Critics of the administration's Central America policy have questioned whether extensive U.S. military activity in Honduras has had the side effect of contributing to Honduran and CIA support for anti-Sandinista rebels headquartered there. They note, for example, that a rebel official has said an airfield at El Aguacate in central Honduras that was improved by the U.S. military has become a base for air supply missions to guerrillas inside Nicaragua.

The Pentagon, which has been conducting military exercises in Honduras since early 1983, repeatedly has said the military is not involved with the rebels or their irregular war, which was financed by the CIA until a congressional funding cutoff last spring.

However, Barnes said through his spokesman: "It the training program demonstrates a direct relationship between U.S. military activities in Honduras and those of the CIA. And it raises a serious question of whether there is other military involvement in other CIA operations" in Honduras.

U.S. government sources stressed that the training of Honduran forces had nothing to do with the covert war in Nicaragua. The appropriate House and Senate committees were notified in advance, as the law requires, one official said, and the operation was kept separate from the CIA's work on behalf of the rebels, often called contras, short for counterrevolutionaries.

"We trained their Honduran people to rescue hostages from buildings and hijacked planes," said one U.S. official. "It has nothing to do with training the contras . . . . We've done this all over."

"The objective is hostages, . . . mostly in urban environments," the official said.

Another government official said the structure for the counterterrorism training program varies depending on the situation in a particular country. On some occasions, the official said, it is a joint CIA-military operation, and in other instances the military does it alone.

In the case of Honduras, the official said, the CIA had a relationship with the Honduran military, and when it was decided -- based on actual situations -- that such training was needed, it was felt that it would be best to do it under the umbrella of the CIA.

Joint military-CIA operations, which flourished during the Vietnam War, have declined in the past decade largely because of reports that the programs were not properly supervised. For example, the Phoenix program in Vietnam, which was a joint military-CIA operation, received considerable criticism following reports that thousands of suspected Viet Cong officials and sympathizers were assassinated.

"We've learned a lot of things about how to do business as a result of Vietnam and things like the Phoenix program," said a Defense Department official. "I'm not saying there's no relationship" between the military and the CIA. "I'm saying this unbridled collaboration that existed in the past has been stopped. It's all very carefully vetted."

The official said that Army Special Forces personnel provide the bulk of the manpower for antiterrorist training. Green Berets who conducted the training program in Honduras were selected from units at Fort Bragg in Fayetteville, N.C., the home of the John F. Kennedy Special Warfare Center.

One of the Green Berets who took part in the Honduras training, Sgt. 1st Class Byron K. Carlisle, was later indicted with another Green Beret on charges of selling explosives and munitions taken from Fort Bragg to undercover federal agents. The other Green Beret charged with Carlisle, Sgt. 1st Class Keith W. Anderson, was not a participant in the training operation. Both have pleaded not guilty.

Anderson's lawyer, in papers filed in federal court in Fort Lauderdale, Fla., said he intends to ask the CIA to produce documents concerning "a classified government operation which allegedly took place in Honduras and Nicaragua concerning the training of contra rebels."

Anderson's attorney, Stephen H. Broudy of Fort Lauderdale, said in an interview that his client will base his defense in part on his belief that the explosives and munitions he and Carlisle are accused of selling were going to the anti-Sandinista rebels.

Law enforcement sources said the scheme did not involve channeling explosives to the rebels.

According to a search warrant affidavit filed by federal agents in court, the explosives were to be traded for drugs and money supplied by the undercover agents.

Benjamin Broudy, Carlisle's attorney and Stephen H. Broudy's brother, said in an interview that his client has a spotless military record and that his involvement in the alleged scheme had nothing to do with receiving cash or drugs.

The Broudys said they hope to subpoena as a witness at the trial a Honduran Special Forces officer, 2nd Lt. Oscar Alvarez. Alvarez is a nephew of Gen. Gustavo Alvarez Martinez, a key U.S. ally and the leader of the Honduran military until fellow officers ousted him last March 31.

According to a letter filed in court by Assistant U.S. Attorney Linnea Johnson, Carlisle said he introduced the undercover agents to Lt. Alvarez after the agents asked to meet him. Johnson quotes Carlisle as saying the "Honduran situation" was discussed at the meeting.

Lt. Alvarez, who was at Fort Bragg at the time attending a Special Forces school for foreign military officers, was not charged with any crime.

Stephen Broudy said he wants to question Lt. Alvarez about U.S. activities in Honduras and "his tie-in with Mr. Anderson and Mr. Carlisle" in an effort to bolster the defense argument that the two soldiers believed the weapons deal was part of a U.S. government-sanctioned operation.

Lt. Alvarez, assigned to the Honduran Special Forces Command, was at La Venta during the training program and, according to a source familiar with the project, became acquainted with Carlisle there.

Lt. Alvarez, who is back in Honduras, said there he knew Carlisle. But he said he met with the undercover agents only to discuss his efforts to help Carlisle in a plan to import wooden fixtures from Honduras. Alvarez declined to answer questions about the secret training program, saying that his superior had told him not to discuss military matters with a reporter.

Gen. Alvarez, his uncle living in exile in the United States, could not be reached for comment.

Members of the Honduran antiterrorist unit have participated in or were on the scene for a half dozen antiterrorist operations since 1982, military sources said.

These included the seizure of 80 prominent Honduran businessmen in a leftist group's September 1982 occupation of a Chamber of Commerce in the Honduran city of San Pedro Sula, where the unit interrogated hostages who had escaped but made no assault; the release of a member of a wealthy family kidnaped in San Pedro Sula, and an assault on a Salvadoran guerrilla safe house in Tegucigalpa in March 1982 in which one guerrilla sympathizer was killed.

A source close to one of the U.S. Special Forces participants in the Honduran training program gave this account of the project:

It began in late 1982 when prospective team members were interviewed in a stark room at the Bordeaux Motor Inn, a Fayetteville, N.C., motel near Fort Bragg.

Following the selection of the six team members and one alternate, a briefing was held at a high-security Special Operation Command building at Fort Bragg.

Officials from the Pentagon and the CIA outlined the training program and stressed that the entire operation was to be carried out with the utmost secrecy. The name of La Venta, the site of the training in the Honduran countryside, was not to be repeated by the Green Berets outside the briefing room, they were told.

They were instructed to grow their hair long and to be "completely sterile" -- to leave home their berets, dog tags and other military identification. Jeans and other civilian attire replaced their uniforms while they were in Honduras.

"They didn't want anybody on the project to be associated with the military," the source said.

The group was divided into two teams of three each and alternated going into Honduras for two or three months at a time during most of 1983. When one team was training at La Venta, the other stayed at Fort Bragg preparing lessons and other activities related to the project.

The training was intensive and covered a broad spectrum of counterterrorist and other military techniques, including sniper shooting, shotgun firing, judo and other forms of hand-to-hand combat, safe-house raids, scuba diving, the clearing of airplanes and combat intelligence techniques. Special instructors were flown in from the United States for such areas as demolition and high-speed photography.

One night the Honduran trainees were taken to Tegucigalpa, where they practiced rappelling down the sides of a hotel under construction.

Visitors from the United States, the U.S. Embassy in Tegucigalpa and the Honduran military came and went from the camp.

On at least two occasions, Gen. Alvarez dropped by, including once for an extensive briefing on the project. He wanted the training to proceed quickly. Lt. Alvarez, a graduate of Texas A&M University, acted as his interpeter during the briefing. Lt. Alvarez is assigned to another unit of the Honduran Special Forces Command, a 150-man, long-range reconnaissance team that, according to military sources, received unclassified U.S. Special Forces training from February through July last year.

Another visitor to the camp was the CIA station chief in Tegucigalpa. He sometimes took target practice at the camp's pistol range.